Simulated performance of a-Si/nc-Si tandem devices on flat substrates and substrates with T_sac (red), T_sp (green) and T_honey (blue) textures. SEM images (top) show surface morphology T_sac, T_sp and T_honey. A) shows the J_sc of the a-Si junction, nc-Si junction and the sum of both junctions for the different substrate types, as a function of nc-Si absorber thickness (d_nc−Si). B) shows the spectral absorptance in each of the layers of the tandem device on T_honey. In addition to the layers indicated in the plot (air, ITO, a-Si, nc-Si, AZO) absorptance in the p-nc-SiO_X:H layer (brown), n-nc-SiO_X:H layers (green) and Ag layer (dark grey, close to bottom horizontal axis) are indicated. C) shows the a-Si and nc-Si absorptance curves and 1-R curves for the different substrate types, for tandem device with d_a−Si = 300 nm and d_nc−Si = 1.2 μm.